This training grant in developmental endocrinology and metabolism at Boston Children's Hospital intends to provide funding for 4 postdoctoral fellows per year to engage in research training leading to independent careers in academic pediatric endocrinology. Trainees enter the program with either the MD, MD/PhD or occasionally the PhD degree, and are selected from highly qualified pediatric endocrinology fellows at Children's Hospital. The 31 trainers include 15 pediatric endocrine physician-scientists (including 12 MD/PhDs), 12 physician-scientists of other disciplines, and 4 PhD scientists. Children's Hospital is the major training site, along with laboratories at Massachusetts General Hospital, Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, and Joslin Diabetes Center. The major areas of research emphasis in this training grant include clinical, translational and basic laboratory research in diabetes mellitus, obesity, neuroendocrinology, bone health, endocrine disruptors, stem cell biology, bioinformatics, and ion transport. Training consists of didactic courses, including in quantitative methods and the ethical conduct of research, and an intensive period of individually mentored research. The intended average duration of training is two years. Of the 29 trainees during the past 15 years who have completed training on this T32 grant, all but 2 are faculty in academic pediatric institutions (1 Professor, 15 Assistant Professors), 2 are in industry, and one is at the FDA. Of these, 9 have had independent NIH K awards, and 2 have one or more R01s. Their record of publication is strong. This program takes advantage of the breadth of scientific expertise of the training faculty within the Division of Endocrinology, as well as in the larger Boston Children's Hospital community and surrounding Harvard environment. Relevance. There is a great shortage of qualified pediatrician-scientists, including pediatric endocrinologists, in the United States today, at a time when the potential for scientific breakthroughs in the treatment of pediatric diseases like obesity and diabetes is great. These diseases are a great threat to the future health of our nation's children. We hope that our program addresses this need by inspiring the early careers of a highly motivated group of pediatric endocrinology trainees immersed in a rigorous and stimulating learning environment.